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/* litmus/sync.c - Support for synchronous and asynchronous task system releases.
*
*
*/
#include <asm/atomic.h>
#include <asm/uaccess.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <litmus/litmus.h>
#include <litmus/sched_plugin.h>
#include <litmus/jobs.h>
#include <litmus/sched_trace.h>
static DECLARE_COMPLETION(ts_release);
static long do_wait_for_ts_release(void)
{
long ret = 0;
/* If the interruption races with a release, the completion object
* may have a non-zero counter. To avoid this problem, this should
* be replaced by wait_for_completion().
*
* For debugging purposes, this is interruptible for now.
*/
ret = wait_for_completion_interruptible(&ts_release);
return ret;
}
int count_tasks_waiting_for_release(void)
{
unsigned long flags;
int task_count = 0;
struct list_head *pos;
spin_lock_irqsave(&ts_release.wait.lock, flags);
list_for_each(pos, &ts_release.wait.task_list) {
task_count++;
}
spin_unlock_irqrestore(&ts_release.wait.lock, flags);
return task_count;
}
static long do_release_ts(lt_t start)
{
int task_count = 0;
unsigned long flags;
struct list_head *pos;
struct task_struct *t;
spin_lock_irqsave(&ts_release.wait.lock, flags);
TRACE("<<<<<< synchronous task system release >>>>>>\n");
sched_trace_sys_release(&start);
list_for_each(pos, &ts_release.wait.task_list) {
t = (struct task_struct*) list_entry(pos,
struct __wait_queue,
task_list)->private;
task_count++;
/* RT tasks can be delayed. Non-RT tasks are released
immediately. */
if (is_realtime(t)) {
litmus->release_at(t, start + t->rt_param.task_params.phase);
}
sched_trace_task_release(t);
}
spin_unlock_irqrestore(&ts_release.wait.lock, flags);
complete_n(&ts_release, task_count);
return task_count;
}
asmlinkage long sys_wait_for_ts_release(void)
{
long ret = -EPERM;
ret = do_wait_for_ts_release();
return ret;
}
asmlinkage long sys_release_ts(lt_t __user *__delay)
{
long ret;
lt_t delay;
/* FIXME: check capabilities... */
ret = copy_from_user(&delay, __delay, sizeof(delay));
if (ret == 0) {
/* Note: Non-rt tasks that participate in a sync release cannot be
delayed. They will be released immediately. */
ret = do_release_ts(litmus_clock() + delay);
}
return ret;
}
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